The present invention relates to a shaft coupling for transmitting a comparatively great torque, particularly by accomodating mutual misalignments of the shafts and/or by absorbing shocks on the shafts.
Shaft couplings for rotating shafts which are capable of transmitting torque despite mutual misalignment thereof are widely used. Among such couplings are flexible couplings which have rubber members or metal springs as elastic elements for accomodating mutual misalignments of the shafts, and the gear couplings which utilize the sliding between teeth of internal and external gears. A flexible coupling which uses such elastic elements as rubber members transmits a small amount of torque compared with other types of couplings, and therefore it cannot be used for transmitting a large torque, say, of several thousand kgs-m. In the gear coupling, the tooth faces subjected to wear or spalling, such damage sometimes causing an increase of space between the teeth, finally making it necessary to replace the coupling itself. In order to prevent wear of the tooth faces, so as to solve the abovementioned drawback, the tooth faces must be lubricated sufficiently, which requires troublesome inspection and maintenance of the coupling, such trouble being undesirable from the standpoint of the recent tendency of reducing the amount of manpower used in industry.
On the other hand, the rollers of a roller table which carry slabs or plates in rolling mills, and machine tools, pumps, air compressors and rolling stocks use a flexible coupling which is for transmitting a smallertorque, say 100 kgs-m, compared with the large amount of torque to be transmitted by the former kind of flexible coupling. For the latter kind of flexible coupling gear couplings are used in most cases, causing the same drawbacks described above. Likewise, disk couplings are used, but they are deficient from the standpoint of strength and accuracy in finishing.
In addition to gear couplings and disk couplings, there are used tire-type flexible rubber couplings which are covered with a high shear strength rubber. There is also another kind of shaft coupling which comprises flat steel springs wound in the form of a grid over specially shaped grooves cut into each hub.
This kind of flexible rubber coupling transmits a smaller amount of torque relative to its great size; moreover, the bolts thereof must be tightened from time to time. The shaft coupling having the flat steel springs requires lublication, and has a tooth face and grid member subjected to severe wear; and its capacity for accomodation of misalignments is small. Both of the abovedescribed shaft couplings have low heat resistance.
Generally shaft couplings must transmit torque and absorb shocks as well as accomodating mutual misalignments of the shafts. In machine tools, there frequently occur sudden changes of the load at the start and finish of operation or during operation. Such sudden changes of the load cause impacts to be produced in the direction of rotation; and if such impacts are produced repeatedly, fatigue failure of the shafts, damage of the key way or like troubles may occur in the driving force transmission system.
In order to absorb impacts in the shafting for transmitting a comparatively great torque in the case of such machinery, there are used clutch couplings, hydraulic transmission couplings or the like, but these couplings do not have the capability of accomodating mutual misalignment of shafts. Therefore, there is strong demand by users of machinery and equipment in various industries for a shaft coupling which can transmit a large torque for a small size, and which can accomodate mutual misalignments of shafts and also absorb shock.